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Acids and Bases

Property	Acid	Base
Definition	Produce H+ ions in aqueous solution	produce OH- ions in aqueous solution
Taste	sour	bitter
Electrolyte	yes	yes
pH	less than 7.0	greater than 7.0
Reaction with Litmus	Blue turns red	Red turns blue
Reaction with Phenolphthalein	clear	pink
Other	Corrosive Used as dehydrating agent Used in Pickling Metals	Dissolves fats Feels slippery

Strong vs. Weak Acids/Bases


Acids and bases are classified as strong or weak by the degree to which they ionize(dissociate) in aqueous solution.

• Strong acids (bases) completely (or nearly completely) ionize in water, while weak acids(bases) only partially ionize.

Concentration

• The concentration of acids and bases is determined by the pH of the solution.
• In this case, the solute is the hydronium ion, H₃O⁺
• The pH scale ranges from 0 - 14
  • The pH scale is a logarhythmic scale - each number on the pH scale represents a factor of ten
  • A solution with a pH of 5.0 is 10 times more acidic than a solution with a pH of 6.0
  • Likewise, a solution with a pH of 12.0 is 100 times more basic than one with a pH of 10.0
• Solutions with a pH less than 7.0 are considered acidic
  • The lower the number, the more acidic the solution
• Solutions with a pH greater than 7.0 are considered basic (alkaline)
  • The higher the pH, the more basic the solution
• Solutions with a pH of 7.0 are considered neutral . They are neither acidic nor basic.
Determining pH
• A pH meter or indicator can be used to determine pH
• Indicators undergo specific color changes when exposed to different pH ranges.

Neutralization

• During a neutralization reaction, hydronium ions from the acid react with hydroxide ions from the base to form water
• The remaining ions combine to form a salt.

Titration

• the process in which a solution of known concentration is used to determine the concentration of another solution
• usually involves acid/base neutralizations

Soaps and Detergents

• Soaps are organic salts
• They are made by reacting fats or oils with sodium hydroxide or potassium hydroxide in a process called saponification.
• The resulting soap has an ionic head(from the base) and a nonpolar hydrocarbon tail (from the fat)
  • The nonpolar tail dissolves any grease, then the ionic head dissolves in the water and carries the dirt away
• Detergents have structures similar to soaps but do not form soap scum when used in hard water. (Soaps do form this scum)

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